SYRIAN forces killed at least 200 people and wounded hundreds in a deadly barrage of shelling early today, activists said.

The offensive was reported in the city of Homs, one of the main flashpoints of opposition to the regime during the uprising against President Bashar Assad.

The reports could not be confirmed independently, but two main opposition groups, the British-based Syrian Observatory for Human Rights and the Local Co-ordination Committees, said the death toll was more than 200.

More than half of the killings - about 140 - were reported in the Khaldiyeh neighbourhood.

"This is the worst attack of the uprising, since the uprising began in March until now," said Rami Abdul-Rahman, the head of the observatory, which tracks violence through contacts on the ground.

It was not immediately clear what precipitated the attack, but there have been reports that army defectors set up checkpoints in the area and were trying to consolidate control.

Assad is trying to crush the revolt with a sweeping crackdown that has so far claimed thousands of lives, but neither the government nor the protesters are backing down and clashes between the military and an increasingly bold and armed opposition has meant many parts of the country have seen relentless violence.

The United Nations Security Council meeting later today will take up a much-negotiated resolution on Syria. A diplomat for a Western nation that sits on the council said the meeting would happen this morning, New York time.

Assad's regime has been intensifying an assault against army defectors and protesters. The UN said weeks ago that more than 5,400 people had been killed in violence since March, but hundreds more have been killed since.